WO2004088881A1

WO2004088881A1 - Optical transmission path failure detection system

Info

Publication number: WO2004088881A1
Application number: PCT/JP2003/004034
Authority: WO
Inventors: Takashi Miyazaki
Original assignee: Fujitsu Limited
Priority date: 2003-03-28
Filing date: 2003-03-28
Publication date: 2004-10-14
Also published as: EP1610475B1; US20050157978A1; EP1610475A1; JPWO2004088881A1; JP4044560B2; US7428354B2; EP1610475A4

Abstract

An optical transmission path failure detection system for detecting failure of an optical transmission path connecting an optical communication device to an optical amplifier corresponding to the communication device. Light emitted from a first light source and incident via a first optical transmission path, an optical amplifier, and a second optical transmission path is detected. When the detected light has a level below a predetermined level, it is judged that the first or the second optical transmission path has failed. When the detected light has a level equal to or above the predetermined level, it is judged that the first and the second optical transmission path are both normal. This can assure detection of failure of an optical transmission path connecting an optical communication device to an optical amplifier.

Description

Optical transmission line failure detection system

The present invention relates to an optical transmission line failure detection system that detects a failure in an optical transmission line that connects an optical communication device and an optical amplifier corresponding to the communication device. Background art

In communication using an optical transmission line, specifically, an optical fiber, a repeaterless system that does not have a repeater that requires power supply on the way may be employed. In this repeaterless system, as a method of extending the transmission distance, an optical amplifier having an erbium-doped fiber (hereinafter referred to as “EDF”) is installed in the middle of the transmission line, and the terminal station (communication device on the transmission side and the reception side) is installed. (Communication equipment on the side) There is a method to excite this EDF with light sent from it. In particular, when the transmission distance is desired to be long, light is transmitted from the terminal station to the EDF in the optical amplifier using an optical fiber dedicated to the pumping light, which is different from the optical fiber for the signal light (for example, Non-Patent Document 1: PB Hansen, L. Eskilden, SG Grubb, AM Vengsarkar, SK Korotky, TA Strasser, JEJ Alphonsus, JJ Veselka, DJ DiGiovanni, DW Peckham, EC Beck, D. Truxal, WY Cheung, SG Kosinski, D. Gasper, PF Wysocki, VL da Silva and JR Simpson, 529km unrepeatered transmission at 2.88Gb it / s using dispersion compensation, forward error correction, and remote post and pre—amplifies pumped by diode pumped Raman lasers, Electronics Letters vol. 31 1 9 9 5 years, 146 0 — 1 461, see http: //www.alcatel, com / submarine / products / ur /). In such an intermediate and relay system, the transmission power of the signal light and the pumping light in the communication device on the transmission side may each be 1 W or more. Therefore, if the transmitting communication device sends such high output power light when the optical fiber is cut, the light irradiated from the cut surface may pose a danger to the human body. is there. Also, a phenomenon called a fiber fuse occurs, and there is a risk that the optical fiber will burn. this Therefore, from the viewpoint of ensuring safety, if the optical fiber that connects the terminal amplifier that is often laid on land and the optical amplifier is cut, the reflected light generated at the cut surface is detected, and the terminal station (For example, refer to Patent Document 1: Japanese Patent Application Laid-Open No. H8-293835), and a monitoring control signal of a low transmission power before both end stations transmit signal light and pumping light. To send signal light and pump light after confirming continuity (for example, Non-Patent Document 2: Toshihiro Otani, Yotenoku, Hiroyuki Deguchi, Hiroyuki Irie, Tsukasa Takahashi, Eiji Ishikawa, Adult Ikeda, Harazawa Shinichiro, "10 GX 3 2 wave 250 km no middle | Development of 1 transmission system", Proc. Of the IEICE 2003 General Conference, _P. 474, B. 10 See 4 4).

However, in the method of detecting the reflected light generated at the cut surface of the optical fiber and stopping the light output from the terminal, the reflected light may not be detected because the reflection is small depending on the shape of the cut surface. is there. Also, when the cut surface is immersed in a liquid such as water, which has a small relative refractive index to glass, the reflection is small and reflected light may not be detected. Also, in the method in which both end stations send monitoring and control signals of low transmission power to each other before sending signal light and pumping light and confirm continuity, and then send signal light and pumping light, the distance between the terminal stations is long. In this case, the transmission control signal of the supervisory control signal sent from one terminal station is low, so that the other terminal station may not be able to receive the supervisory control signal due to attenuation during transmission. Disclosure of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical transmission line fault detection system which solves the above-mentioned problems of the prior art and improves the reliability of optical transmission line fault detection. In order to achieve this object, an optical transmission line fault detection system according to the present invention includes an optical transmission line fault detection system for detecting a fault in an optical transmission line connecting an optical communication device and an optical amplifier corresponding to the optical communication device. A first light source connected to the optical amplifier by a first optical transmission line and transmitting light to the first optical transmission line; a first light source transmitted from the first light source; First light detecting means for detecting light transmitted through the optical amplifier and the second optical transmission path; and the level of light detected by the first light detecting means is less than a predetermined level. In some cases, any one of the first and second optical transmission lines A first failure determination unit that determines that a failure has occurred in the force, and determines that the first and second optical transmission paths are normal when the force is equal to or higher than a predetermined level.

The optical transmission line fault detection system according to the present invention includes an optical transmission line connecting a communication device, which is a terminal station, and an optical transmission line between a communication device and an optical amplifier corresponding to the communication device, for example, on land. And the optical transmission line power between the optical amplifiers. When the optical transmission line is installed on the sea floor, light leaking from the optical transmission line between the communication device and the optical amplifier corresponding to the communication device is dangerous to the human body. Considering that it is highly possible to cause a failure, an optical transmission path failure between the communication device and an optical amplifier corresponding to the communication device is detected. In this optical transmission line failure detection system, a communication device and an optical amplifier corresponding to the communication device are connected by a first optical transmission line, and the first light source and the optical amplifier are connected by a second optical transmission line. When the level of the light that is connected and transmitted from the first light source and incident through the second optical transmission path, the optical amplifier, and the first optical transmission path is equal to or lower than a predetermined level, It is determined that a failure has occurred in the first optical transmission line. In the conventional method of detecting the reflected light generated on the cut surface of the optical transmission line, the reflected light may not be detected because the reflection is small depending on the shape of the cut surface. However, according to the present invention, when a failure such as disconnection occurs in the optical transmission line, the level of the light transmitted and incident through the optical transmission line is surely reduced. By detecting the failure, the reliability of failure detection can be improved. In addition, since faults are not detected by sending low transmission power signals between the communication devices that are terminal stations, even if the distance between the communication devices is long, the communication device and the communication device can be used. The reliability of detection of a fault that has occurred in an optical transmission path between the optical amplifier and the optical amplifier can be improved. BRIEF DESCRIPTION OF THE FIGURES

Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.

FIG. 1 is a diagram illustrating a first configuration example of the optical transmission system.

FIG. 2 is a diagram illustrating a second configuration example of the optical transmission system.

FIG. 3 is a diagram illustrating a third configuration example of the optical transmission system.

FIG. 4 is a diagram illustrating a first configuration example of the excitation light detection unit. FIG. 5 is a diagram illustrating a second configuration example of the excitation light detection unit.

FIG. 6 is a diagram illustrating a third configuration example of the excitation light detection unit. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a first configuration example of an optical transmission system having the optical transmission line fault detection system of the present invention. The optical transmission system shown in the figure includes an excitation light source 102, an excitation light detection unit 104, a failure determination unit 106, a signal light transmission unit 120, and an excitation light source 102, which are configured in a communication device on the transmitting station side. Optical power amplifier 140, optical amplifier 160 corresponding to the communication device on the transmitting station side, excitation light source 202 included in the communication device on the receiving station side, excitation light detecting section 204, failure It comprises a determining unit 206, a signal light receiving unit 220, an optical power blur 240, and an optical amplifier 260 corresponding to a communication device on the receiving station side.

The optical amplifier 160 includes an erbium-doped fiber (EDF) 162 and an optical power coupler 164. Further, the optical power amplifier 140 in the communication device on the transmitting station side and the EDF 162 in the optical amplifier 160 are connected by an optical fiber 150, and the excitation light source 1 in the communication device on the transmitting station side is connected. The optical power blur 16 in the optical amplifier 16 is connected to the optical fiber 16 in the optical amplifier 16. The optical amplifier 260 includes an EDF 262 and an optical power plug 2 264. Further, the optical power plug 240 in the communication device on the receiving station side and the EDF 262 in the optical amplifier 260 are connected by an optical fiber 250, and the pumping in the communication device on the receiving station side is performed. The light source 202 and the optical power plug 264 in the optical amplifier 260 are connected by an optical fiber 252.

In this optical transmission system, signal light is transmitted from the communication device on the transmitting station side to the communication device on the receiving station side. This signal light is transmitted through the optical fibers 150, 350 and 250. The pump light source 102, pump light detector 104, and fault determiner 106 in the communication equipment on the transmitting station side are optical transmission line faults that detect faults in the optical fibers 150 and 152. A detection system (hereinafter referred to as “transmission side optical transmission line fault detection system”) is configured. On the other hand, the excitation light source 202, the excitation light detection unit 204, and the failure determination unit 206 in the communication device on the receiving station side are optical transmission lines that detect failures of the optical fibers 250 and 250. Constructs a failure detection system (hereinafter referred to as "the receiver optical transmission line failure detection system") I do.

Hereinafter, the operation of the optical transmission system shown in FIG. 1 is performed before the signal light is transmitted from the communication device on the transmitting station side to the communication device on the receiving station side. In the first embodiment for detecting the failure of the 25 2, and while the signal light is being transmitted from the communication device on the transmitting station side to the communication device on the receiving station side, the optical fibers 150, 15 2, and 2 A description will be given of a second embodiment for detecting 50 and 25 failures.

First, a first embodiment will be described. The pumping light source 102 constituting the transmission-side optical transmission path fault detection system in the transmission-side communication device transmits light with a predetermined low transmission power. For example, the pump light source 102 transmits light at 1 OmW, which is a transmission power of class 1 or less. Light from the excitation light source 102 is transmitted through the optical fiber 152 and is incident on the optical power blur 1664 in the optical amplifier 160.

The optical power bra 1 64 is, for example, a wavelength-multiplexed power bra with low loss, and can change the light transmission destination for each wavelength. This optical power plug 16 4 makes the light from the optical fiber 15 2 incident on the EDF 16 2. The light incident on the EDF 162 is attenuated, passes through the EDF 162, is further transmitted through the optical fiber 150, and is incident on the optical power plug 140. The optical power bra 140 is, for example, a wavelength-division multiplex coupler having a small loss, similarly to the optical power plug 164. The optical power plug 140 causes the light from the optical fiber 150 to enter the excitation light detection unit 104.

The excitation light detector 104 detects the incident light. Further, the excitation light detector 104 compares the level of the detected light with a first predetermined level. The comparison result is sent to failure determination unit 106.

The failure determination unit 1 • 6 determines whether or not the optical fibers 150 and 152 have a failure, based on the comparison result from the excitation light detection unit 104. Specifically, when the comparison result from the excitation light detection unit 104 indicates that the level of light incident on the excitation light detection unit 104 is equal to or higher than a first predetermined level. think of. In this case, since the loss of light from the excitation light source 102 to the excitation light detection unit 104 is small, the failure determination unit 106 includes the optical fibers 150 and 1502. Is determined to be normal. On the other hand, the comparison result from the excitation light detection unit 104 indicates that the level of light incident on the excitation light detection unit 104 is lower than the first predetermined level. Consider the case. In this case, since the loss of light from the pumping light source 102 to the pumping light detecting unit 104 is large, the failure determining unit 106 includes the optical fibers 150 and 1502. Is determined to have failed.

When the optical fiber 150 and 152 are determined to be normal, the chapter P damage determining unit 106 instructs the signal light transmitting unit 120 to start transmitting signal light. At the same time, it instructs the excitation light source 102 to increase the light transmission power to a level at which the EDF 162 is appropriately excited. The signal light transmission section 120 starts transmission of signal light in response to an instruction from the failure determination section 106. On the other hand, the excitation light source 102 increases the transmission power of optical excitation to a level at which the EDF 162 is appropriately excited in accordance with an instruction from the failure determination unit 106. As a result, the signal light from the signal light transmitting unit 120 is amplified by the EDF 162 and sent to the communication device on the receiving side. When determining that a failure has occurred in one of the optical fibers 150 and 152, the failure determination unit 106 instructs the pump light source 102 to stop transmitting light. The excitation light source 102 stops transmitting light according to this instruction.

On the other hand, the pumping light source 202 constituting the receiving side optical transmission line fault detection system in the receiving side communication device has a predetermined low transmission power (for example, a transmission power of less than class 1) like the excitation light source 102. Transmit light at 1 O mW). The light from the excitation light source 202 is transmitted through the optical fiber 252 and is incident on the optical power plug 264 in the optical amplifier 260.

The optical power bra 2 64 is, for example, a low-loss wavelength multiplex power bra, and makes light from the optical fiber 25 2 incident on the EDF 26 2. The light incident on the EDF 262 passes through the EDF 262 while attenuating, is further transmitted through the optical fiber 250, and is incident on the optical power blur 240. The optical power bra 240 is, for example, a wavelength multiplex power bra with a small loss, similar to the optical power bra 264, and makes the light from the optical fiber 250 incident on the excitation light detecting section 204.

The excitation light detector 204 detects the incident light, similarly to the excitation light detector 104. Further, the excitation light detector 204 compares the detected light level with a second predetermined level. The comparison result is sent to the failure determination unit 206.

The failure determination unit 206 is, like the failure determination unit 106, a ratio of the excitation light detection unit 204 Based on the comparison result, it is determined whether or not the optical fibers 250 and 250 have a failure. Specifically, the comparison result from the excitation light detection unit 204 is

If the level of light incident on 204 is equal to or higher than the second predetermined level, the damage determination unit 206 in Chapter P determines that the optical fibers 250 and 252 are normal. It is determined that. On the other hand, the comparison result from the excitation light detection unit 204 is

If the level of the light incident on 4 is less than the second predetermined level, the fault determination unit 206 determines that the fault has occurred in one of the optical fibers 250 and 252. Is determined to have occurred.

If the failure determination unit 206 determines that the optical fibers 250 and 250 are normal, the failure determination unit 206 determines the level at which the EDF 262 is appropriately excited with respect to the excitation light source 202. It is instructed to make the pumping path of the light excitation go up. In response to this indication, the pump light source 202 increases the output power of the optical pump to a level at which the EDF 262 is properly pumped. As a result, the signal light passing through the EDF 262 is amplified and sent to the communication device on the receiving side.

In addition, when the failure determination unit 206 determines that a failure has occurred in any of the optical fibers 250 and 250, the failure determination unit 206 instructs the pump light source 202 to stop transmitting light. . The excitation light source 202 stops transmitting light according to this instruction.

Next, a second embodiment will be described. The excitation light source 102 constituting the transmission-side optical transmission line fault detection system in the transmission-side communication device appropriately excites the EDF 162 and receives the signal light from the signal light section 120. The pump light is transmitted at a predetermined high transmission power in order to transmit it to the communication device on the side. The pump light has a wavelength different from that of the signal light transmitted from the signal light transmitting unit 120. The pumping light from the pumping light source 102 is transmitted through the optical fiber 152 and is incident on the optical power plug 164 in the optical amplifier 160.

The optical power plug 16 4 is transmitted from the signal light transmitting unit 12 0, and the signal light transmitted through the optical power bra 1 40, the optical fiber 1 50 and the EDF 16 2 Send to. The optical power plug 16 4 enters the EDF 16 2 with respect to the excitation light from the optical fiber 15 2. The excitation light incident on the EDF 16 2 passes through the EDF 16 2 while being attenuated, and is further transmitted through the optical fiber 150 so that the optical power It is incident on 0. The optical power blur 140 enters the optical fiber 150 for the signal light transmitted from the signal light transmitting unit 120, and the excitation light detecting unit 104 for the excitation light from the optical fiber 150. Incident on.

The excitation light detector 104 detects the incident excitation light. Further, the excitation light detector 104 compares the detected level of the excitation light with a third predetermined level. The comparison result is sent to the failure determination unit 106.

The failure determination unit 106 determines whether or not a failure has occurred in the optical fibers 150 and 152 based on the comparison result from the excitation light detection unit 104. Specifically, similarly to the first embodiment, the comparison result from the excitation light detection unit 104 indicates that the level of the excitation light incident on the excitation light detection unit 104 is equal to or higher than the third predetermined level. If this is the case, the failure determination unit 106 determines that the optical fibers 150 and 152 are normal. On the other hand, if the level of the comparison light from the excitation light detection unit 104 indicates that the level of the excitation light incident on the excitation light detection unit 104 is less than the third predetermined level, P The chapter damage determining unit 106 determines that a failure has occurred in any of the optical fibers 150 and 152.

When determining that a failure has occurred in any of the optical fibers 150 and 152, the chapter P harm determination unit 106 transmits the signal light to the signal light unit 120. In addition to instructing the stop, the pump light source 102 is instructed to stop the transmission of the pump light. The signal light transmitting unit 120 stops transmitting the signal light in response to an instruction from the failure determining unit 106. On the other hand, the pumping light source 102 stops transmitting the pumping light in response to an instruction from the failure determination unit 106.

On the other hand, when the failure determination unit 106 determines that the optical fibers 150 and 152 are normal, the failure determination unit 106 does not issue an instruction to the signal light transmission unit 120 and the pump light source 102. ,. For this reason, the signal light transmitting unit 120 continues transmitting the signal light, and the pumping light source 102 continues transmitting the exciting light. ■ On the other hand, in the communication equipment on the receiving side, the pumping light source 202 constituting the optical transmission line fault detection system on the receiving side excites the EDF 262 appropriately, similarly to the pumping light source 102. In order to transmit the signal light from the signal light transmitting unit 120 to the communication device on the receiving side, the pumping light is transmitted at a predetermined high transmission power. The pump light is transmitted to the signal light transmitter 1 It has a different wavelength from the signal light transmitted from 20. Excitation light from the excitation light source 202 is transmitted through the optical fiber 252 and is incident on the optical power blur 2664 in the optical amplifier 260.

The optical power plastic 2 64 is transmitted from the signal light transmitting unit 120, and the optical power plastic 140, the optical fiber 150, the EDF 16 2, the optical plastic 16 4 and the optical fiber 3 5 0 The signal light that has passed through and the pump light that has been transmitted from the pump light source 202 and has passed through the optical fiber 25 2 enter the EDF 26 2. The signal light and the pump light incident on the EDF 262 pass through the EDF 262, are further transmitted through the optical fiber 250, and are incident on the optical power plug 240. The optical power plug 240 altates signal light to the signal light receiving section 220 and enters excitation light to the excitation light detecting section 204.

The excitation light detector 204 detects the incident excitation light, similarly to the excitation light detector 104. Further, the excitation light detector 204 compares the detected level of the excitation light with a fourth predetermined level. The comparison result is sent to the failure determination unit 206.

Like the failure determination unit 106, the failure determination unit 206 has a failure in the optical fibers 250 and 250 based on the comparison result from the excitation light detection unit 204. Determine whether it is strong or not. Specifically, as in the first embodiment, the comparison result from the excitation light detection unit 204 indicates that the level of the excitation light incident on the excitation light detection unit 204 is equal to or higher than the fourth predetermined level. In this case, the failure determination unit 206 determines that the optical fibers 250 and 250 are normal. On the other hand, when the comparison result from the excitation light detection unit 204 indicates that the level of the excitation light to be supplied to the excitation light detection unit 204 is less than the fourth predetermined level, The failure determination unit 206 determines that a failure has occurred in any of the optical fibers 250 and 250.

Further, when it is determined that a failure has occurred in any of the optical fibers 250 and 252, the failure determination unit 206 instructs the pump light source 202 to stop transmitting the pump light. . The pumping light source 202 stops transmitting the pumping light in response to the instruction from the chapter P damage determining unit 206. Therefore, the pump light is not transmitted through the optical fibers 250 and 252. Also, even if the signal light is transmitted from the signal light transmitting section 120, the EDF 262 is not excited, and therefore the signal light cannot be transmitted through the optical fiber 250. On the other hand, the failure determination unit 206 determines that the optical fibers 250 and 250 are normal. In this case, no instruction is given to the excitation light source 202. Therefore, the excitation light source 202 continues transmitting the excitation light.

FIG. 2 is a diagram showing a second configuration example of the optical transmission system having the optical transmission line fault detection system of the present invention. The optical transmission system shown in FIG. 2 is different from the optical transmission system shown in FIG. 1 in that an optical amplifier 1660 is provided between the optical fiber 150 and the EDF 162 in the optical amplifier 160. The optical power bra 16 and the excitation light source 170 included in the communication device on the transmitting station side are connected via the optical fiber 154 and the excitation light source 1 in the communication device on the transmitting station side. An optical power bra 180 is provided between the optical power bra 2 and the optical power bra 16 in the optical amplifier 16 0, and the excitation light detecting unit 17 2 is connected to the optical power bra 180. . In the optical amplifier 260, an optical power plug 266 is provided between the optical fiber 250 and the EDF 262, and the optical power plug 266 and the receiving station side are connected via the optical fiber 254. In the communication device on the receiving station side, the excitation light source 270 and the optical power plug 264 in the optical amplifier 260 are connected to the excitation light source 270 in the communication device. The optical power plug 280 is provided, and the excitation light detecting section 272 is connected to the optical power plug 280.

In the optical transmission system shown in FIG. 2, similarly to the optical transmission system shown in FIG. 1, signal light is transmitted from the communication device on the transmitting station side to the communication device on the receiving station side. This signal light is transmitted through the optical filters 150, 350 and 250. The excitation light source 102, the excitation light detection unit 104, the failure determination unit 106, the excitation light source 170, and the excitation light detection unit 172 in the communication device on the transmitting station side are optical fiber 150, An optical transmission line fault detection system (transmission side optical transmission line fault detection system) that detects 15 2 and 15 4 faults is configured. On the other hand, the excitation light source 202, the excitation light detection unit 204, the failure determination unit 206, the excitation light source 270 and the excitation light detection unit 272 in the communication equipment on the receiving station side are connected to the optical fiber 2 An optical transmission line fault detection system (receiving side optical transmission line fault detection system) that detects 50, 25, and 25 4 faults is configured.

Hereinafter, the operation of the optical transmission system shown in FIG. 2 will be described before the optical fibers 150, 152, 154, In the third embodiment for detecting the faults of 250, 255, and 254, and when the signal light is being transmitted from the communication device on the transmitting station side to the communication device on the receiving station side, the optical fiber 1 5 0, 1 A description will be given of a fourth embodiment for detecting a failure of 52, 154, 250, 250 and 254.

First, a third embodiment will be described. The pumping light source 102 constituting the transmission-side optical transmission path fault detection system in the transmission-side communication device transmits light with a predetermined low transmission power. Light from the excitation light source 102 is incident on the optical power blur 180. The optical power blur 180 is, for example, a wavelength-division multiplexing coupler having a small loss, and transmits light from the excitation light source 102 to the optical power blur 16 4 in the optical amplifier 160 via the optical fiber 152. Incident. The optical power plug 1 6 4 is, for example, a wavelength-division multiplex power bra with low loss.

Light from 52 is incident on the EDF 16 2. The light incident on the EDF 162 passes through the EDF 162 while being attenuated, and is incident on the optical power plug 166. Light power plastic 1

Reference numeral 66 denotes, for example, a wavelength-division multiplexing coupler having a small loss, and the light from the EDF 162 is incident on the optical fiber 150. The optical power blur 140 is, for example, a wavelength-multiplexed power blur with a small loss, and makes the light from the optical fiber 150 incident on the excitation light detector 104. The excitation light detector 104 detects the incident light. Further, the excitation light detector 104 compares the detected light level with a fifth predetermined level. The comparison result is sent to failure determination unit 106.

The failure determination unit 106 indicates that the comparison result from the excitation light detection unit 104 indicates that the level of light incident on the excitation light detection unit 104 is equal to or higher than a fifth predetermined level. If there is, the optical fibers 150 and 152 are determined to be normal. On the other hand, the failure determination unit 106 determines that the comparison result of the excitation light detection unit 104 indicates that the level of light incident on the excitation light detection unit 104 is less than the fifth predetermined level. If it indicates that a failure has occurred, it is determined that a failure has occurred in one of the optical fibers 150 and 152. The excitation light source 170 transmits light at a predetermined low transmission power. The light transmitted from the excitation light source 170 has a different wavelength from the light transmitted from the excitation light source 102. Light from the excitation light source 170 enters the optical power blur 1666. The optical power blur 1666 enters the light from the excitation light source 170 into the EDF 162. The light incident on the EDF 162 passes through the EDF 162 while attenuating, and is incident on the optical power plug 164. The optical power plug 16 4 is transmitted from the excitation light source 17 0, passes through the optical fiber 15 4, the optical power plug 16 6 and the EDF 16 2, and enters the optical fiber 15 2 . light The force brush 180 makes the light from the optical fiber 152 incident on the excitation light detecting section 1702. The excitation light detecting section 172 detects the incident light. Further, the excitation light detecting section 172 compares the level of the detected light with a sixth predetermined level. The comparison result is sent to failure determination unit 106.

The failure determination unit 106 indicates that the comparison result from the excitation light detection unit 172 indicates that the level of light incident on the excitation light detection unit 172 is equal to or higher than the sixth predetermined level. If they are present, it is determined that the optical fibers 152 and 154 are normal. On the other hand, the fault determination unit 106 determines that the comparison result from the excitation light detection unit 172 indicates that the level of light incident on the excitation light detection unit 172 is lower than the sixth predetermined level. If it indicates, it is determined that a failure has occurred in one of the optical fibers 152 and 154. When the failure determiner 106 determines that the optical fibers 150, 152 and 154 are normal, it starts transmitting the signal light to the signal light transmitter 120. At the same time, it instructs the pump light sources 102 and 170 to increase the light transmission power to a level at which the EDF 162 is appropriately pumped. The signal light transmission unit 120 starts transmission of the signal light in response to an instruction from the failure determination unit 106. On the other hand, the excitation light sources 102 and 170 increase the transmission power of the optical excitation to a level at which the EDF 162 is appropriately excited according to the instruction from the failure determination unit 106. As a result, the signal light from the signal light transmitting unit 120 is amplified by the EDF 162 and transmitted to the communication device on the receiving side.

In addition, when the failure determination unit 106 determines that a failure has occurred in any of the optical fibers 150, 152, and 154, the failure determination unit 106 responds to the pump light sources 102 and 170. Instructs to stop transmitting light. The excitation light sources 102 and 170 stop transmitting light according to this instruction.

On the other hand, the pumping light source 202 constituting the receiving side optical transmission line fault detection system in the receiving side communication device transmits light at a predetermined low transmission power, similarly to the pumping light source 102. Light from the excitation light source 202 is incident on the optical power plug 280. The optical power plug 280 is, for example, a low-loss wavelength multiplexing power bra. The optical power plug 280 in the optical amplifier 260 receives the light from the excitation light source 202 via the optical filter 255. It is incident on 4.

The optical power bra 2 6 4 is, for example, a wavelength-multiplexed power bra with a small loss. The light from 52 enters the EDF 26 2. The light incident on the EDF 262 passes through the EDF 262 while being attenuated, and is incident on the optical power plug 266. Light Bra 2

Reference numeral 66 denotes, for example, a wavelength-division multiplexing coupler having a small loss, and the light from the EDF 262 is incident on the optical fiber 250. The optical power blur 240 is, for example, a wavelength-multiplexed power blur with a small loss, and makes light from the optical fiber 250 incident on the excitation light detector 204. The excitation light detector 204 detects the incident light. Further, the excitation light detector 204 compares the detected light level with a seventh predetermined level. The comparison result is sent to the failure determination unit 206.

The failure determination unit 206 determines that the comparison result from the excitation light detection unit 204 indicates that the level of light incident on the excitation light detection unit 204 is equal to or higher than a seventh predetermined level. If there is, the optical fibers 250 and 250 are determined to be normal. On the other hand, the failure determination unit 206 determines that the comparison result of the excitation light detection unit 204 indicates that the level of light incident on the excitation light detection unit 204 is lower than the seventh predetermined level. If this indicates that a failure has occurred in any of the optical fibers 250 and 252. The excitation light source 270 transmits light at a predetermined low transmission power. The light transmitted from the excitation light source 270 has a different wavelength from the light transmitted from the excitation light source 202. Light from the excitation light source 270 is incident on the optical power plug 266. The optical power plug 266 inputs the light from the excitation light source 270 to the EDF 262. The light incident on the EDF 262 passes through the EDF 262 and is incident on the optical power plug 264. The optical power plug 264 is transmitted from the excitation light source 270 and passes through the optical fiber 254, the optical power plug 266, and the EDF 262 to direct the light to the optical fiber 252. . The optical power plug 280 inputs the light from the optical fiber 252 to the excitation light detector 272.

The excitation light detector 272 detects the incident light. Further, the excitation light detector 272 compares the level of the detected light with an eighth predetermined level. The comparison result is sent to the failure determination unit 206.

The failure determination unit 206 shows that the comparison result from the excitation light detection unit 272 indicates that the level of light incident on the excitation light detection unit 272 is equal to or higher than the eighth predetermined level. If they are present, it is determined that the optical fibers 255 and 254 are normal. On the other hand, the fault determination unit 206 determines that the comparison result from the excitation light detection unit 272 is If it indicates that the level of light incident on 72 is less than the eighth predetermined level, it is determined that a failure has occurred in one of optical fibers 252 and 254. If it is determined that the optical fibers 250, 252, and 254 are normal, the failure determination unit 206 increases the transmission power of the optical pump to the level at which the EDF 262 is appropriately pumped to the pump light sources 202 and 270. Instruct them to do so. Pump light sources 202 and 270 increase the power of the light pump to the level at which EDF 262 is properly pumped in response to this indication. As a result, the signal light passing through the EDF 262 is amplified and sent to the communication device on the receiving side.

When determining that any of the optical fibers 250, 252, and 254 has failed, the failure determining unit 206 instructs the pump light sources 202 and 270 to stop transmitting light. The excitation light sources 202 and 270 stop transmitting light in response to this instruction.

Next, a fourth embodiment will be described. The pumping light source 102 constituting the transmission side optical transmission line fault detection system in the transmission side communication device appropriately excites the EDF 162 and transmits the signal light from the signal light transmission unit 120 to the reception side communication device. For this purpose, the pump light is transmitted at a predetermined high transmission power. Note that the pump light has a different wavelength from the signal light transmitted from the signal light transmitting unit 120. The excitation light from the excitation light source 102 is transmitted through the optical fiber 152 via the optical power bra 180 and is incident on the optical power plug 164 in the optical amplifier 160.

The optical power bra 164 is transmitted from the signal light transmitting unit 120, and the signal light transmitted through the optical power bra 140, the optical fiber 150, the optical power plug 166, and the EDF 162 is transmitted to the communication device on the receiving side. . Further, the optical power bra 164 enters the EDF 162 with respect to the excitation light from the optical fiber 152. The excitation light that has entered the EDF 162 passes through the EDF 162 and enters the optical power plug 166. The optical power plug 166 enters the EDF 162 for the signal light transmitted from the signal light transmission unit 120, and enters the optical fiber 150 for the excitation light from the EDF 162. The optical power plug 140 enters the optical fiber 150 with respect to the signal light transmitted from the signal light transmitting unit 120, and enters the excitation light detection unit 104 with respect to the excitation light from the optical fiber 150. The excitation light detector 104 detects the incident light. Further, the excitation light detector 104 compares the detected light level with a ninth predetermined level. The comparison result is sent to failure determination unit 106.

The failure determination unit 106 indicates that the comparison result from the excitation light detection unit 104 indicates that the level of light incident on the excitation light detection unit 104 is equal to or higher than a ninth predetermined level. If there is, the optical fibers 150 and 152 are determined to be normal. On the other hand, the failure determination unit 106 determines that the comparison result from the excitation light detection unit 104 indicates that the level of light incident on the excitation light detection unit 104 is less than the ninth predetermined level. If it indicates, it is determined that a failure has occurred in one of the optical fibers 150 and 152. The light transmitted from the pump light source 170 has a different wavelength from the light transmitted from the pump light source 102 and the signal light transmitter 120. The light from the excitation light source 170 enters the optical power blur 1666 through the optical fiber 154. The optical power blur 1666 makes the light from the excitation light source 170 enter the EDF162. The light incident on the ED 162 passes through the ED 162 and is incident on the optical power plug 164. The optical power plug 16 4 is transmitted from the excitation light source 17 0, passes through the optical fiber 15 4, the optical power plug 16 6 and the EDF 16 2, and enters the optical fiber 15 2. The optical power plug 180 makes the light from the optical fiber 152 incident on the excitation light detection unit 1702.

The excitation light detecting section 172 detects the incident light. Further, the excitation light detecting section 172 compares the detected light level with the 10th predetermined level. The comparison result is sent to the failure determination unit 106.

The failure determination unit 106 shows that the comparison result from the excitation light detection unit 172 indicates that the level of the light incident on the excitation light detection unit 172 is equal to or higher than the 10th predetermined level. If it is, it is determined that the optical fibers 152 and 154 are normal. On the other hand, the failure determination unit 106 determines that the comparison result from the excitation light detection unit 172 indicates that the level of the light Alt to the excitation light detection unit 172 is lower than the predetermined level of 10th. Indicates that a failure has occurred in one of the optical fibers 152 and 154.The failure determination unit 106 determines that the optical fibers 150, 152 and 154 If it is determined that a failure has occurred in any of them, the signal light transmitting unit 120 is instructed to stop transmitting the signal light. And instruct the excitation light sources 102 and 170 to stop transmitting the excitation light. The signal light transmitting unit 120 stops transmitting the signal light in response to an instruction from the chapter P damage determining unit 106. On the other hand, the excitation light sources 102 and 170 stop transmitting the excitation light in response to an instruction from the failure determination unit 106.

Further, when the failure determining unit 106 determines that the optical fibers 150, 152, and 154 are normal, the signal light transmitting unit 120, the pump light sources 102, and 1 Do not give instructions to 70. For this reason, the signal light transmitting unit 120 continues transmitting the signal light, and the excitation light sources 102 and 170 continue transmitting the excitation light.

On the other hand, the pumping light source 202 constituting the optical transmission line fault detection system on the receiving side in the communication device on the receiving side appropriately excites the EDF 262 to generate a signal from the signal light transmitting section 120. In order to transmit the light to the communication device on the receiving side, the excitation light is transmitted at a predetermined high transmission power. The pump light has a wavelength different from that of the signal light transmitted from the signal light transmitter 120. Excitation light from the excitation light source 202 is transmitted through the optical fiber 252 via the optical power plug 280 and is incident on the optical power bra 264 in the optical amplifier 260.

The optical power bra 2 6 4 is transmitted from the signal light transmitting unit 120 power, the optical power bra 1 40, the optical fiber 150, the optical power bra 1 66, the EDF 1 62, the optical power bra 1 The signal light passing through the optical fiber 350 and the pump light transmitted from the pumping light source 202 and passing through the optical fiber 250 enter the EDF 262. The signal light and the pump light incident on the EDF 262 pass through the EDF 262, are further transmitted through the optical fiber 250, and are incident on the optical power plug 266.

The optical power bra 2 66 causes the signal light and the excitation light to enter the optical power bra 2 40. The optical power plug 240 receives the signal light transmitted from the signal light transmitting unit 120 into the signal light receiving unit 220, and receives the pump light from the pump light source 202 into the pump light detecting unit 2 Inject into 0 4.

The excitation light detector 204 detects the incident light. Further, the excitation light detector 204 ′ compares the detected light level with a first predetermined level. The comparison result is sent to failure determination unit 206.

The failure determination unit 206 determines whether the comparison result from the excitation light detection unit 204 is If the level of light incident on the section 204 is equal to or higher than the first predetermined level, it is determined that the optical fibers 250 and 250 are normal. On the other hand, the failure determination unit 206 determines that the comparison result from the excitation light detection unit 204 indicates that the level of light incident on the excitation light detection unit 204 is less than the first predetermined level. Indicates that a failure has occurred in any of the optical fibers 250 and 250. The pumping light source 270 transmits light at a predetermined low transmission power. Note that the light transmitted from the excitation light source 270 has a different wavelength from the light transmitted from the excitation light source 202 and the signal light transmission unit 120. The light from the excitation light source 270 enters the optical power plug 266 via the optical fiber 254. The optical power plug 266 inputs the light from the excitation light source 270 to the EDF 262. The light incident on the EDF 262 passes through the EDF 262 and enters the optical power plug 264. The optical power plug 264 is transmitted from the excitation light source 170 and passes through the optical fiber 254, the optical power plug 266 and the EDF 262, and enters the optical fiber 252. . The optical power plug 280 makes the light from the optical fiber 252 incident on the excitation light detector 272.

The excitation light detector 272 detects the incident light. Further, the excitation light detector 272 compares the level of the detected light with a predetermined second level. The comparison result is sent to the chapter P damage determination unit 206.

The failure determination unit 206 shows that the comparison result from the excitation light detection unit 272 indicates that the level of light incident on the excitation light detection unit 272 is equal to or higher than the first predetermined level. If it is, it is determined that the optical fibers 255 and 254 are normal. On the other hand, the failure determination unit 206 determines that the comparison result from the excitation light detection unit 272 indicates that the level of the light incident on the excitation light detection unit 272 is less than the first predetermined level. Indicates that a failure has occurred in one of the optical fibers 252 and 2554.The failure determination unit 206 determines that the optical fibers 250, 252 and 254 If it is determined to be normal, no instructions are given to the excitation light sources 202 and 270. Therefore, the pump light, the sources 202 and 270 continue transmitting the pump light.

In addition, the failure determination unit 206 is connected to one of the optical fibers 250, 250 and 250. If it is determined that chapter P damage has occurred, an instruction is issued to the excitation light sources 202 and 270 to stop transmitting light. The excitation light sources 202 and 270 stop transmitting light according to this instruction. For this reason, the pump light is not transmitted through the optical fibers 250, 250, and 254. Further, even if the signal light is transmitted from the signal light transmitting unit 120, the EDF 262 is not excited, and thus the signal light is not transmitted through the optical fiber 250.

FIG. 3 is a diagram showing a third configuration example of the optical transmission system having the optical transmission line fault detection system of the present invention. The optical transmission system shown in FIG. 3 is different from the optical transmission system shown in FIG. 1 in that the excitation light source 102 is connected to the optical power blur 140 and the excitation light detector 104 is connected to the optical fiber 18 2 through the optical power bra 18. An excitation light source 174 is connected to the optical power plug 182. On the other hand, in the communication device on the receiving side, the excitation light source 202 is connected to the optical power plug 240, and the excitation light detection unit 204 is connected to the optical fiber 282 via the optical power blur 282. It is connected to the. An excitation light source 274 is connected to the optical power plug 282.

In the optical transmission system shown in FIG. 3, as in the optical transmission system shown in FIG. 1, signal light is transmitted from the communication device on the transmitting station side to the communication device on the receiving station side. This signal light is transmitted through the optical fibers 150 and 250. Excitation light source 102, excitation light detector 104, and failure determiner 106 in the communication equipment on the transmitting station side are optical transmission line failures that detect failures of optical fibers 150 and 152. Configure the detection system (transmission side optical transmission line fault detection system). On the other hand, the excitation light source 202, the excitation light detection unit 204, and the failure determination unit 206 in the communication device on the receiving station side are optical transmission lines that detect failures in the optical fibers 250 and 252. Construct a failure detection system (optical transmission line failure detection system on the receiving side).

Hereinafter, the operation of the optical transmission system shown in FIG. 3 will be described before the optical fibers 150, 152, 250 and 250 are transmitted before the signal light is transmitted from the communication device on the transmitting station side to the communication device on the receiving station side. In the fifth embodiment for detecting the failure of the second and fifth optical fibers, and while the signal light is being transmitted from the communication device on the transmitting station side to the communication device on the receiving station side, the optical fibers 150, 152, 2 A description will be given of a sixth embodiment for detecting 50 and 25 failures. First, a fifth embodiment will be described. The pumping light source 102 constituting the transmission-side optical transmission path fault detection system in the transmission-side communication device transmits light with a predetermined low transmission power. Light from the excitation light source 102 is incident on the optical power bra 140. The optical power bra 140 is, for example, a low-loss wavelength multiplexing coupler, and the light from the pump light source 102 is incident on the EDF 16 2 in the optical amplifier 160 via the optical fiber 150. . The light incident on the EDF 162 passes through the EDF 162 while being attenuated, and is incident on the optical power coupler 164. The optical power bra 16 4 is, for example, a low-loss wavelength multiplexing coupler, and the light from the EDF 16 2 is incident on the optical fiber 15 2. The optical power plug 182 is, for example, a wavelength-division multiplex coupler with a small loss, and makes the light from the optical fiber 152 incident on the excitation light detecting unit 104.

The excitation light detector 104 detects the incident light. Further, the excitation light detector 104 compares the detected light level with a first predetermined third level. The comparison result is sent to the failure determination unit 106.

The P-part damage determination unit 106 determines that the comparison result from the excitation light detection unit 104 indicates that the level of light incident on the excitation light detection unit 104 is equal to or higher than the predetermined third level. If it indicates, it is determined that the optical fibers 150 and 152 are normal. On the other hand, the P-part damage determination unit 106 determines that the comparison result from the excitation light detection unit 104 indicates that the level of light incident on the excitation light detection unit 104 is less than the first predetermined level. If it indicates that one of the optical fibers 150 and 152 has failed, the failure determiner 106 determines that the optical fibers 150 and 152 are normal. If it is determined that there is, the signal light transmission unit 120 is instructed to start transmitting the signal light, and the EDF 162 is appropriately transmitted to the excitation light sources 102 and 174. It instructs to start transmitting the pump light by increasing the light transmission power to the level to be pumped. The signal light transmitting unit 120 starts transmission of the signal light in response to an instruction from the failure determining unit 106. On the other hand, the pumping light sources 102 and 174 increase the pumping power of the optical pumping to a level at which the EDF 162 is appropriately pumped according to the instruction from the failure determination unit 106, and Start sending. The light transmitted from the excitation light source 174 has a different wavelength from the light transmitted from the excitation light source 102 and the signal light transmission unit 120. Excitation light source 1 7 The light from 4 passes through the optical power plug 18 2, the optical fiber 15 2 and the optical power plug 16 4 to excite the EDF 16 2. As a result, the signal light from the signal light transmission unit 120 is amplified and sent to the communication device on the receiving side.

When determining that a failure has occurred in one of the optical fibers 150 and 152, the failure determination unit 106 instructs the pump light source 102 to stop transmitting light. The excitation light source 102 stops transmitting light according to this instruction.

On the other hand, in the communication device on the receiving side, the excitation light source 202 constituting the optical transmission line fault detection system on the receiving side transmits light with a predetermined low transmission power. Light from the excitation light source 202 is incident on the optical power blur 240. The optical power blur 240 is, for example, a wavelength-division multiplexing coupler having a small loss. The light from the pump light source 202 is incident on the EDF 262 in the optical amplifier 260 through the optical fiber 250. . The light incident on the EDF 262 passes through the EDF 262 while being attenuated, and is incident on the optical power plug 264. The optical power puller 264 is, for example, a wavelength multiplex power puller with a small loss, and makes the light from the EDF 262 incident on the optical fiber 255. The optical power plug 282 is, for example, a wavelength loss multi-gravity bra with a small loss, and makes the light from the optical fiber 252 incident on the excitation light detector 204. The excitation light detector 204 detects the incident light. Further, the excitation light detector 204 compares the detected light level with a first predetermined level. The comparison result is sent to failure determination unit 206. The failure determination unit 206 determines that the comparison result from the excitation light detection unit 204 indicates that the level of light incident on the excitation light detection unit 204 is equal to or higher than the first predetermined level. If so, the optical fibers 250 and 250 are determined to be normal. On the other hand, the failure determination unit 206 determines that the comparison result from the excitation light detection unit 204 indicates that the level of light incident on the excitation light detection unit 204 is lower than the first predetermined level. Indicates that a failure has occurred in one of the optical fibers 250 and 252.The failure determination unit 206 determines that the optical fibers 250 and 252 are normal. If it is determined, increase the light transmission power to the level at which the EDF 262 is appropriately pumped with respect to the pump light sources, 202 and 274, and start transmitting the pump light. Instruct. The excitation light sources 202 and 274 are controlled by the EDF 26 2. The transmission of the pump light is started by increasing the transmission power of the optical pump to a level at which 2 is appropriately pumped. The light transmitted from the excitation light source 274 has a different wavelength from the light transmitted from the excitation light source 202 and the signal light transmission unit 120. The excitation light, light from the source 274, passes through the optical power plug 282, the optical fiber 252 and the optical power plug 264 to excite the EDF 262. As a result, the signal light from the signal light transmitting section 220

The signal is amplified by the DF 262 and transmitted to the communication device on the receiving side via the optical fiber 250.

When determining that a failure has occurred in any of the optical fibers 250 and 52, the failure determination unit 206 instructs the pump light source 202 to stop transmitting light. The excitation light source 202 stops transmitting light according to this instruction.

Next, a sixth embodiment will be described. The excitation light source 102 constituting the transmission-side optical transmission line fault detection system in the transmission-side communication device appropriately excites the EDF 162 to receive the signal light from the signal light transmission unit 120 on the reception side. The pumping light is transmitted at a predetermined high transmission power in order to transmit the communication light to the communication device. The pump light has a different wavelength from the signal light transmitted from the signal light transmitter 120. The excitation light from the excitation light source 102 is transmitted through the optical fiber 150 through the optical power plug 140 and is transmitted to the EDF 162. The excitation light incident on the EDF 162 is , Passing through the relevant EDF 16 2

It is incident on the optical power plug 16 4.

The optical power bra 16 4 is transmitted from the signal light transmitting unit 12 0, and the signal light passing through the optical power bra 1 40, the optical fiber 150 5 and the EDF 16 2 is transmitted to the communication device on the receiving side. Send to Further, the optical power bra 16 4 is transmitted from the excitation light source 102, and the optical fiber 150 5 is used for the excitation light passing through the optical power bra 140, the optical fiber 150 and the EDF 16 2. Light is incident on 2. The excitation light that has entered the optical fiber 15 2

The light enters the excitation light detection unit 104 via 2. .

The excitation light detector 104 detects the incident excitation light. Furthermore, the excitation light detector 1

In step 04, the level of the detected excitation light is compared with a fifteenth predetermined level. The comparison result is sent to the failure determination unit 106.

The failure determination unit 106 determines that the comparison result from the excitation light detection unit 104 indicates that the level of the excitation light to be applied to the excitation light detection unit 104 is equal to or higher than the 15th predetermined level. In this case, the chapter P damage determination unit 106 determines that the optical fibers 150 and 152 are normal. On the other hand, when the comparison result from the excitation light detection unit 104 indicates that the level of the excitation light incident on the excitation light detection unit 104 is lower than the 15th predetermined level. The failure determination unit 106 determines that a failure has occurred in any of the optical fibers 150 and 152.

When the failure determiner 106 determines that a failure has occurred in any of the optical fibers 150 and 152, it instructs the signal light transmitter 120 to stop transmitting signal light. Both of them instruct the excitation light sources 102 and 174 to stop transmitting the excitation light. The signal light transmitting unit 120 stops transmission of the signal light in response to an instruction from the failure determination unit 106. On the other hand, the excitation light sources 102 and 174 stop transmitting the excitation light in response to the instruction from the failure determination unit 106.

On the other hand, when the failure determiner 106 determines that the optical fibers 150 and 152 are normal, the fault determiner 106 issues an instruction to the signal light transmitter 120 and the pump light sources 102 and 174. Do not do. For this reason, the signal light transmitting unit 120 continues transmitting the signal light, and the pump light sources 102 and 174 continue transmitting the pump light.

On the other hand, in the communication equipment on the receiving side, the excitation light sources 202 and 274 constituting the optical transmission line fault detection system on the reception side are the same as the excitation light sources 102 and 174, and the EDF 266 In order to appropriately excite the signal and transmit the signal light from the signal light transmitting unit 120 to the communication device on the receiving side, the pumping light is transmitted at a predetermined high transmission rate. The pump light has a wavelength different from that of the signal light transmitted from the signal light transmitter 120. Excitation light from the excitation light source 202 is transmitted through the optical fiber 250 through the optical power plug 240 and is incident on the EDF 262. The excitation light incident on the EDF 262 is further incident on the optical power blur 264.

The optical power bra 2 64 is transmitted from the signal light transmitting unit 120, the optical power bra 140, the optical fiber 150, the EDF 16 2, the optical power 16 4 and the optical fiber 3 The signal light passing through 50 enters the EDF 262. The optical power plug 264 is transmitted from the excitation light source 202, and the excitation light transmitted through the optical power plug 240, the optical fiber 250, and the EDF 262 is transmitted through the optical fiber 250. Incident on. The excitation light incident on the optical fiber 252 is incident on the excitation light detection unit 204 via the optical power blur 282. The excitation light detector 204 detects the incident excitation light. Further, the excitation light detector 204 compares the detected level of the excitation light with a 16th predetermined level. The comparison result is sent to the Chapter P damage determination unit 206.

The failure determination unit 206 determines that the comparison result from the excitation light detection unit 204 indicates that the level of the excitation light incident on the excitation light detection unit 204 is equal to or higher than the 16th predetermined level. In this case, the failure determination unit 206 determines that the optical fibers 250 and 250 are normal. On the other hand, when the comparison result from the excitation light detection unit 204 indicates that the level of the excitation light incident on the excitation light detection unit 204 is less than the 16th predetermined level. The failure determination unit 206 determines that a failure has occurred in any of the optical fibers 250 and 250.

When determining that one of the optical fibers 250 and 250 has failed, the failure determination unit 206 instructs the excitation light sources 202 and 274 to stop transmitting the excitation light. I do. The excitation light sources 202 and 274 stop transmitting the excitation light in response to an instruction from the failure determination unit 206. Thus, the pump light is not transmitted through the optical fibers 250 and 250. Further, even if the signal light is transmitted from the signal light transmitting unit 120, the EDF 262 is not excited, so that the signal light is not transmitted through the optical fiber 250.

On the other hand, when the failure determiner 206 determines that the optical fibers 250 and 250 are normal, the failure determiner 206 does not issue an instruction to the pump light sources 202 and 274. Therefore, the excitation light sources 202 and 274 continue transmitting the excitation light.

FIG. 4 to FIG. 6 are diagrams illustrating a configuration example of the excitation light detection unit 104. Note that the excitation light detectors 170, 204, and 272 also have the same configuration as the excitation light detector 104. The excitation light detector 104 shown in FIG. 4 includes a photodiode 108, an amplifier 110, and a comparator 112. The photodiode 108 converts input light into an electric signal and outputs the electric signal. The amplifier 110 amplifies this electric signal and outputs it to the comparator 112. The comparator 112 compares the level (voltage) of the input electric signal with a predetermined identification level (W), which is a predetermined level, and compares the comparison result with the fault determination unit 106. Output to

The excitation light detector 104 shown in FIG. 5 is different from the one shown in FIG. It has a configuration provided with an optical filter 114 before. The optical filter 114 outputs only light of a predetermined wavelength out of the input light. By providing the optical filter 114, the excitation light detection unit 104 can extract only the excitation light even when the incident light contains both the signal light and the excitation light. Become.

The excitation light detector 104 shown in FIG. 6 is different from that shown in FIG. 5 in that the comparator 112 is able to determine the level (m ±) of the input electric signal and the light transmission power of the excitation light source 102 and the like. Compares with proportionate Australia. Before the transmission of signal light from the communication device on the transmitting station side to the communication device on the receiving station side, the pump light source 102 and the like emit low light to detect a failure in the optical fiber 150 and the like. The transmitter transmits light, but when the transmission of signal light from the communication device on the transmitting station side to the communication device on the receiving station starts, the EDF 162 in the optical amplifier 160 is excited. The optical transmission power is very large, reaching 1 W or more. Therefore, by setting the discrimination level to a voltage proportional to the optical transmission power of the excitation light source 102, for example, when a failure occurs in the optical fiber 150, etc. after the transmission of the signal light has started, Even if the level of the excitation light in the excitation light detector 104 was reduced due to the fault, the optical fiber 150 etc. would be erroneously detected as normal due to the low identification level. As described above, in the optical transmission system according to the present embodiment, the communication device can be disconnected to any one of the optical fibers 150 and the like that connect the optical amplifier 160 and the like corresponding to the communication device. When a failure occurs, the level of the light that is transmitted and transmitted through the optical fiber 150 or the like in which the failure has occurred is reliably reduced, so that the excitation light 104 or the like detects the level of the light. By doing so, the certainty of fault detection It is possible to above. In addition, since faults are not detected by transmitting low transmission power signals between the communication devices that are the terminal stations, even when the distance between the communication devices is long, the communication device and the communication device can be used. It is possible to improve the reliability of detecting a failure that has occurred in the optical fiber 150 or the like between the optical amplifier 160 and the like.

Further, when a failure occurs in the optical fiber 150, etc., the transmission of light by the signal light transmitting unit 120, the excitation light source 102, etc. is stopped, so that the optical fiber 150, etc. When laid, the optical power S leaks from the optical fiber 150 etc., causing a danger to the human body. Can be prevented.

The optical fibers 15 2 and 25 2 correspond to the first optical transmission line described in the claims, the excitation light sources 102 and 202 correspond to the first light source, and the optical fibers 150 and The reference numeral 250 corresponds to the second optical transmission line, the excitation light detection units 104 and 204 correspond to the first light detection means, and the failure determination units 106 and 206 correspond to the first optical transmission line. Corresponds to the fault determination means, the first start instruction means, the first increase instruction means, the first and second stop instruction means. Further, the optical fibers 154 and 254 correspond to the third optical transmission line described in the claims, the pumping light sources 170 and 270 correspond to the second light source, and the pumping light detecting section 170. 2 and 272 correspond to the second light detection means, and the Chapter P damage determination units 106 and 206 correspond to the second failure determination means, the second start instruction means, the second increase instruction means, Corresponds to the third and fourth stop instruction means

Claims

The scope of the claims

1 · In an optical transmission line fault detection system for detecting a fault in an optical transmission line connecting an optical communication device and an optical amplifier corresponding to the optical communication device,

A first light source connected to the optical amplifier by a first optical transmission line and transmitting light to the first optical transmission line;

First light detection means for detecting light transmitted from the first light source and incident via the first optical transmission line, the optical amplifier and the second optical transmission line,

If the level of light detected by the first light detecting means is lower than a predetermined level, it is determined that a failure has occurred in any of the first and second optical transmission lines, and if the level is equal to or higher than a predetermined level. First failure determining means for determining that the first and second optical transmission lines are normal;

An optical transmission line fault detection system comprising:

2. In the optical transmission line failure detection system according to claim 1,

A first start instruction for instructing the optical communication device to start transmitting signal light when the first failure determination unit determines that the first and second optical transmission paths are normal; An optical transmission line fault detection system comprising a means.

3. The optical transmission line failure detection system according to claim 1 or 2, wherein the first failure determination unit determines that the first and second optical transmission lines are normal. An optical transmission line fault detection system comprising first increase instructing means for instructing a light source for exciting an amplifier to increase light transmission power.

4. The optical transmission line failure detection system according to any one of claims 1 to 3, wherein the first failure determination unit determines that a failure has occurred in any of the first and second optical transmission lines. An optical transmission line failure detection system comprising first stop instruction means for instructing the optical communication device to stop transmitting signal light when the optical communication device has a failure.

5. The optical transmission line failure detection system according to any one of claims 1 to 4, wherein the first failure determination unit determines that a failure has occurred in any of the first and second optical transmission lines. An optical transmission line failure detection system including second stop instruction means for instructing the first light source to stop transmitting light when the first light source is stopped.

Five

6.The optical transmission line fault detection system according to any one of claims 1 to 5, wherein the second optical transmission line is connected to the optical amplifier by a third optical transmission line, and excites light to the third optical transmission line. Light source,

A second light detection unit that is excited by the second light source and detects light incident through the third optical transmission line, the fit optical amplifier, and the first optical transmission line;

If the level of light detected by the second light detection means is lower than a predetermined level, it is determined that a failure has occurred in any of the first and third optical transmission paths, and if the level is equal to or higher than a predetermined level. Second failure determining means for determining that the first and third optical transmission paths are normal;

Optical transmission line fault detection system equipped with L5.

7. In the optical transmission line failure detection system according to claim 6,

If the first and second failure determination means determine that the first to third optical transmission paths are normal, the optical communication apparatus instructs the optical communication apparatus to start transmitting signal light. An optical transmission line fault detection system including second start instruction means.

8. The optical transmission line failure detection system according to claim 6, wherein the first and second failure determination units determine that the first to third optical transmission lines are normal. An optical transmission line fault detection system comprising: a second increase instructing unit that instructs a light source that excites the optical amplifier to increase light transmission power.

9. The optical transmission line failure detection system according to any one of claims 6 to 8, wherein a failure occurs in any of the first to third optical transmission lines by the first and second failure determination means. If it is determined that the transmission of the signal light to the optical communication device is stopped. An optical transmission line failure detection system including third stop instruction means for instructing stop.

10. In the optical transmission line failure detection system according to any one of claims 6 to 9, a failure occurs in any of the first and third optical transmission lines by the first and second failure determination means. An optical transmission line failure detection system comprising: fourth stop instruction means for instructing the first and second light sources to stop transmitting light when it is determined that the first and second light sources have stopped.